Christoph Hellwig <hch@xxxxxxxxxxxxx> 于2018年12月5日周三 下午10:40写道：
>
> Can you please also send a patch to not show this attribute for
> drivers without a timeout handler? Thanks!
>
Do you means checking q->mq_ops->timeout is NULL or not ?
static void blk_mq_rq_timed_out(struct request *req, bool reserved)
{
req->rq_flags |= RQF_TIMED_OUT;
If it's NULL, only re-start a timer for this request in blk_add_timer.
Is there some defect ? if show this attribute and the driver doesn't
support timeout handler ？
if (req->q->mq_ops->timeout) {
enum blk_eh_timer_return ret;
ret = req->q->mq_ops->timeout(req, reserved);
if (ret == BLK_EH_DONE)
return;
WARN_ON_ONCE(ret != BLK_EH_RESET_TIMER);
}
blk_add_timer(req);
}
> On Wed, Dec 05, 2018 at 10:17:06PM +0800, Weiping Zhang wrote:
> > Add documentation for /sys/block/<disk>/queue/io_timeout.
> >
> > Signed-off-by: Weiping Zhang <zhangweiping@xxxxxxxxxxxxxx>
> > ---
> > Documentation/ABI/testing/sysfs-block | 10 ++++++++++
> > Documentation/block/queue-sysfs.txt | 7 +++++++
> > 2 files changed, 17 insertions(+)
> >
> > diff --git a/Documentation/ABI/testing/sysfs-block b/Documentation/ABI/testing/sysfs-block
> > index dea212db9df3..f254a374710a 100644
> > --- a/Documentation/ABI/testing/sysfs-block
> > +++ b/Documentation/ABI/testing/sysfs-block
> > @@ -271,3 +271,13 @@ Description:
> > size of 512B sectors of the zones of the device, with
> > the eventual exception of the last zone of the device
> > which may be smaller.
> > +
> > +What: /sys/block/<disk>/queue/io_timeout
> > +Date: November 2018
> > +Contact: Weiping Zhang <zhangweiping@xxxxxxxxxxxxxx>
> > +Description:
> > + io_timeout is a request’s timeouts at block layer in
> > + milliseconds. When the underlying driver starts processing
> > + a request, the generic block layer will start a timer, if
> > + this request cannot be completed in io_timeout milliseconds,
> > + a timeout event will occur.
> > diff --git a/Documentation/block/queue-sysfs.txt b/Documentation/block/queue-sysfs.txt
> > index 2c1e67058fd3..f0c9bbce73fd 100644
> > --- a/Documentation/block/queue-sysfs.txt
> > +++ b/Documentation/block/queue-sysfs.txt
> > @@ -67,6 +67,13 @@ If set to a value larger than 0, the kernel will put the process issuing
> > IO to sleep for this amont of microseconds before entering classic
> > polling.
> >
> > +io_timeout (RW)
> > +---------------
> > +This is a request’s timeouts at block layer in milliseconds. When the
> > +underlying driver starts processing a request, the generic block layer
> > +will start a timer, if this request cannot be completed in io_timeout
> > +milliseconds, a timeout event will occur.
> > +
> > iostats (RW)
> > -------------
> > This file is used to control (on/off) the iostats accounting of the
> > --
> > 2.14.1
> >
> ---end quoted text---
